linux-kernel - Re: [PATCH v6 4/4] drm: renesas: rz-du: mipi

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Message-ID: <CA+V-a8sZfTgOENXfR2NnykgjGHd+2-vS9Jk-dNLWTVQyAGbQTw@mail.gmail.com>
Date: Mon, 16 Jun 2025 11:48:03 +0100
From: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To: Biju Das <biju.das.jz@...renesas.com>
Cc: Geert Uytterhoeven <geert+renesas@...der.be>, Andrzej Hajda <andrzej.hajda@...el.com>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
	"laurent.pinchart" <laurent.pinchart@...asonboard.com>, Jonas Karlman <jonas@...boo.se>, 
	Jernej Skrabec <jernej.skrabec@...il.com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, 
	Magnus Damm <magnus.damm@...il.com>, 
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>, 
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>, 
	"linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>, 
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH v6 4/4] drm: renesas: rz-du: mipi_dsi: Add support for
 RZ/V2H(P) SoC

Hi Biju,

Thank you for the review.

On Fri, Jun 13, 2025 at 7:17 AM Biju Das <biju.das.jz@...renesas.com> wrote:
>
> Hi Prabhakar,
>
> > -----Original Message-----
> > From: Prabhakar <prabhakar.csengg@...il.com>
> > Sent: 30 May 2025 18:19
> > Subject: [PATCH v6 4/4] drm: renesas: rz-du: mipi_dsi: Add support for RZ/V2H(P) SoC
> >
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> >
> > Add DSI support for Renesas RZ/V2H(P) SoC.
> >
> > Co-developed-by: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
> > Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > ---
> > v5->v6:
> > - Made use of GENMASK() macro for PLLCLKSET0R_PLL_*,
> >   PHYTCLKSETR_* and PHYTHSSETR_* macros.
> > - Replaced 10000000UL with 10 * MEGA
> > - Renamed mode_freq_hz to mode_freq_khz in rzv2h_dsi_mode_calc
> > - Replaced `i -= 1;` with `i--;`
> > - Renamed RZV2H_MIPI_DPHY_FOUT_MIN_IN_MEGA to
> >   RZV2H_MIPI_DPHY_FOUT_MIN_IN_MHZ and
> >   RZV2H_MIPI_DPHY_FOUT_MAX_IN_MEGA to
> >   RZV2H_MIPI_DPHY_FOUT_MAX_IN_MHZ.
> >
> > v4->v5:
> > - No changes
> >
> > v3->v4
> > - In rzv2h_dphy_find_ulpsexit() made the array static const.
> >
> > v2->v3:
> > - Simplifed V2H DSI timings array to save space
> > - Switched to use fsleep() instead of udelay()
> >
> > v1->v2:
> > - Dropped unused macros
> > - Added missing LPCLK flag to rzv2h info
> > ---
> >  .../gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c    | 345 ++++++++++++++++++
> >  .../drm/renesas/rz-du/rzg2l_mipi_dsi_regs.h   |  34 ++
> >  2 files changed, 379 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c b/drivers/gpu/drm/renesas/rz-
> > du/rzg2l_mipi_dsi.c
> > index a31f9b6aa920..ea554ced6713 100644
> > --- a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
> > +++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
> > @@ -5,6 +5,7 @@
> >   * Copyright (C) 2022 Renesas Electronics Corporation
> >   */
> >  #include <linux/clk.h>
> > +#include <linux/clk/renesas-rzv2h-dsi.h>
> >  #include <linux/delay.h>
> >  #include <linux/io.h>
> >  #include <linux/iopoll.h>
<snip>
> > +
> > +static int rzv2h_dphy_conf_clks(struct rzg2l_mipi_dsi *dsi, unsigned long mode_freq,
> > +                             u64 *hsfreq_millihz)
> > +{
> > +     struct rzv2h_plldsi_parameters *dsi_parameters = &dsi->dsi_parameters;
> > +     unsigned long status;
> > +
> > +     if (dsi->mode_calc.mode_freq_khz != mode_freq) {
> > +             status = rzv2h_dphy_mode_clk_check(dsi, mode_freq);
> > +             if (status != MODE_OK) {
> > +                     dev_err(dsi->dev, "No PLL parameters found for mode clk %lu\n",
> > +                             mode_freq);
> > +                     return -EINVAL;
> > +             }
> > +     }
> > +
> > +     clk_set_rate(dsi->vclk, dsi->mode_calc.mode_freq_hz);
>
> Not sure, Can we use the DSI divider required based on the data rate (vclk, bpp and numlanes) here
>
> and then the set parent clk of PLLDSI as well here (dsi->vclk * the divider value) ??
>
> 24MHZ->PLL DSI->DSI DIVIDER->VCLOCK
>
> Maybe then the clock framework has all the information for setting PLL_DSI and DSI_DIVIDER clks??
>
Can you please elaborate here with a detailed example.

Cheers,
Prabhakar